The invention relates to improvements in bipolar medical coagulation instruments of the type disclosed, for example, in U.S. Pat. No. 4,732,149 granted Mar. 22, 1988 to Sutter for "Bipolar Medical Coagulation Instrument". The disclosure of this patent is incorporated herein by reference.
A bipolar medical coagulation instrument normally comprises a forceps with two elongated legs each having a jaw at one end and an electric terminal at the other end. The legs are electrically insulated from each other. A switch which is carried by one of the legs is closed in response to pivoting of the legs in directions to engage the two jaws with one another and additional pivoting while the jaws continue to engage each other. The switch is provided at the inner side of the one leg and is connected with a third terminal by a conductor which ensures that the forceps receives high-frequency electrical energy in response to actual closing of the switch. As a rule, the switch comprises one or more projections which can be caused to engage blank surfaces when the switch is closed to thus establish an electrical connection with the high-frequency generator. The conductor which connects the switch with the third terminal is glued to the respective leg of the forceps or is loosely inserted into a shrinkable hose which surrounds the one leg. The hose is desirable and advantageous because it ensures reliable insulation of the forceps. However, if the shrinking of the hose does not result in the making of an envelope3 which closely follows the outline of the one leg in the region of the switch, foreign matter (such as a cleaning fluid) is likely to penetrate into the improperly shrunk hose. The cleaning fluid can cause additional stretching of and actual damage to the hose.
Bonding of the conductor to the one leg of the forceps is not always satisfactory because the adhesive which is used to bond the conductor to the forceps cannot stand those temperatures which are necessary during shrinking of insulating hoses onto the legs of the forceps.
Another drawback of heretofore known bipolar medical coagulation instruments is that their jaws are likely to assume improper positions (e.g., by overlapping or crossing each other) as a result of that additional pivoting of the legs which is needed to close the switch subsequent to movement of the jaws into engagement with one another. Misalignment of jaws is likely to take place if the jaws are pointed and very narrow, a configuration which is often necessary in order to carry out a particular coagulating operation. Even minor shifting of the jaws from their optimum positions relative to each other can effect the coagulating operation.